A new knee or hip could mean pounds lost as well

Hip and knee replacement surgery is supposed to alleviate pain and allow people to move better and lead a more active lifestyle. A new study published recently in the journal Orthopedics shows that could be the case, because weight loss may be one side effect of getting new knees and hips.

Researchers looked at pre- and post-surgery weight in 196 randomly selected patients who had hip or knee replacement surgery from 2005 to 2007 due to osteoarthritis. Their body mass index was noted before surgery, and patients were followed for an average 20 months. A 5% weight reduction was considered significant weight loss.

Instead of just calculating how much weight patients gained or lost over the course of the study, researchers factored in how much weight people naturally gain on average per year from ages 29 to 73. Generally, they noted, men gain an average 8.8 pounds and women an average 7.6 pounds over eight years.

After adjusting for that natural weight gain, a trend could be seen toward lower weight and BMI after surgery. Among all participants, after correcting for weight gain, 19.9% showed significant weight loss.

Those who had knee replacements had a more substantial decrease in BMI than those who had hip replacements, and those who were obese at the start of the study also lost more weight than their lighter counterparts.

Researchers concluded that although getting a new knee or hip won't cure obesity, the results from the study suggest that such surgery may be the catalyst to getting people to lose weight. What might help even more, they added, is including diet and exercise guidance in the mix.

In a news release, lead author Dr. Michael Bronson said, "Both total knee patients and total hip patients experienced a statistically significant and clinically significant corrected weight loss following surgery, which indicates a healthier overall lifestyle." Bronson is chief of joint replacement surgery at Mount Sinai School of Medicine in New York City.